Detection of X-rays and gamma-rays has a large number of important applications such as national security, medical imaging, astrophysics, and gamma-ray spectroscopy.
Conventional detectors based on Ge and Si have the disadvantage that they require the converter element to be cryogenically cooled. This makes the detectors very complex and expensive.
A special development has been the use of so-called room temperature detectors based on novel heavy compound semiconductors, e.g. Cadmium Zinc Telluride (CZT), which do not require cryogenic cooling.
US20100252744 discloses a room temperature radiation detector that comprises a converter element and a plurality of electrode systems arranged on said element, wherein each electrode system comprises a primary electrode and a supplementary electrode, which are connected to a readout circuitry. The primary and the supplementary electrodes may particularly be realized by planar, parallel stripes extending in a common plane, wherein said stripes are electrically connected above said plane.
It is, however, a problem with the above detector that it is unable to determine the location of an event within the converter element.
U.S. Pat. No. 6,002,134 discloses cross-strip radiation detector for detecting ionizing radiation comprising an array of anodes and a single control electrode common to all anodes.
It is, however, a problem with the above detector that by using only a single control electrode (drift electrode), only simple focusing of the electrons on the anodes is possible. “Kuvvetli, I.; Budtz-Jørgensen, C.: “Charge Collection and Depth Sensing Investigation on CZT Drift Strip Detectors”, IEEE Nuclear Science Symposium Conference Record NSS (R7-2), 2010” discloses a CZT based detector comprising a plurality of detector strip electrodes, and a plurality of drift strip electrodes. The drift strip electrodes are connected to a voltage source that supplies a bias voltage, whereby electrons are steered towards the detector strip electrodes.
By providing each detector electrode with a readout channel the spatial location of the event within the converter element may be estimated.
The miniaturization required to achieve a high spatial resolution is, however, difficult and complex.
Thus, it remains a problem to provide a radiation detector for detecting X-ray and gamma-ray radiation having an improved spatial resolution.